Collect. Czech. Chem. Commun. 1998, 63, 1851-1868

Role of Energy Dissipation and Surface Mobility in Heterogeneous Catalysis by Metals

Zlatko Knor and Jan Plšek

J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 182 23 Prague 8, Czech Republic


The fundamental role of excess energy dissipation and of surface species mobility, both in the preparation of model metallic catalysts (bimetallic catalysts, bimetallic oxide-supported catalysts), and in the activation of reactant molecules on the catalyst surfaces (single crystals, bimetallic and bimetallic oxide-supported catalysts) are discussed. A generalized model of surface interactions is proposed which satisfactorily explains the trapping of particles from the gas phase at the atomic steps and recovery of the trapping sites due to migration of the trapped species towards flat terraces. Higher probability of encounter of these species with other reactants on flat terraces and easier desorption of the reaction products from there in comparison with the bound state at the edges of atomic steps can be expected. Results of FIM and FEM studies of Pt, Dy-W, Pd-W and Pd-Mo systems are used to illustrate selected features of the proposed general model.

Keywords: Surface mobility; Energy dissipation; Trapping sites; Catalysis by metals; Reaction zone; Field emission microscopies; Heterogeneous catalysis.